Sewage Could Help Make Up For Overwhelmed COVID-19 Test Sites

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As Quebec and other provinces update their testing guidelines in response to the record rise in new COVID-19 cases, numerous experts warn that daily COVID-19 reports issued by these governments no longer provide an accurate description of the progress of the COVID-19. pandemic.

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But the content of a community’s wastewater could provide a more accurate picture.

While scientists across the country have been tracking the presence of COVID-19 in wastewater since the beginning of the pandemic, they say this process is particularly valuable as public health authorities struggle to keep up with the spread. of the highly transmissible Omicron variant.

“We have this problem where we have reached the limit of our ability to administer screening tests,” said Mark Servos, a researcher at the University of Waterloo. “But wastewater doesn’t care if people have been tested or are asymptomatic.

“Everyone who goes to the bathroom is included in our analysis.”

The process is tedious and laborious, according to Servos, but results can be obtained in a matter of hours. And while sewage analysis does not provide exact data on the number of COVID-19 cases, it can allow public health officials to identify areas with high infection rates.

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According to Christopher Mody, an infectious disease specialist at the University of Calgary, positive results obtained from PCR tests only represent about a sixth or an eighth of the total number of cases. This discrepancy is expected to increase as more people rely on self-administered rapid tests or simply don’t get tested.

“We need to know what the real number is,” Mody said, adding that the wastewater analysis could help make up for the lack of data. “I would say that wastewater is an extremely useful tool for assessing the magnitude of the disease burden.”

In addition to measuring the extent of transmission, the researchers say analyzing COVID-19 sewage on a regular basis would allow public health officials to identify which variants are dominant in the community.

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Data collected last week in Saskatoon, for example, showed an 87.7 percent increase in viral load in the city’s sewage, including an 808.2 percent increase in the presence of the Omicron variant.

Despite the potential benefits of sewage testing in Quebec, where a variety of factors have led to an underreporting of new COVID-19 cases, the province recently stopped funding a project that did just that.

Sarah Dorner, a Polytechnique Montréal professor who had been helping run the COVID-19 sewage sample investigation, said funding for the six-month pilot project ended in early December.

“We had no more funds to continue,” he wrote in an email, adding that his team had observed “a rapid increase in SARS-CoV-2” in Montreal’s wastewater just before the project was halted.

“Public health is no longer interested,” Dorner told the Montreal Gazette at the time.